The present invention relates to hydrostatic multi-motor drive units and, more particularly, to such a unit with at least two hydraulic motors acting upon a common load.
Hydraulic drives with two motors are known in essentially two different versions or designs.
In a first design both drives are rigidly interconnected by a shaft and, hence, both run permanently. In arrangements in which at least one of the motors is designed to be adjustable, and for attaining high speeds, this motor is set to zero by adjusting its displacement volume to zero. It is disadvantageous that the motor which is set to zero is dragged along by the other motor and, as a result of this, high mechanical losses occur.
To avoid such problems, two-motor drive designs are known in which the two motors are interconnected by gears and couplings, so that in the operating ranges in which the adjustable motor is set to zero, this motor can be mechanically disconnected from the second motor. The disadvantage of this solution is in the high complexity of the coupling and arrangement of gears which is necessary in order to guarantee synchronization of the two machines when engaging and disengaging, so that a smooth transition between the various different operating ranges is made possible.
In DE 100 60 679 A1 an additional hydrostatic two-motor drive unit is disclosed in which two motors are connected with at least one coupling. Such a drive unit encounters the above-described disadvantages.
It would be a great advantage to provide a hydrostatic multi-motor drive unit that overcomes the above problems and disadvantages.